git-post-checkout.sh

#!/bin/bash

# Git post checkout hook.
# Reminds you of South migration changes when switching branches.
# Can be useful when you are when you are testing out a branch from
# someone else that requires migrations.
# Put the file in .git/hooks/post-checkout

PREVIOUS_HEAD=$1
NEW_HEAD=$2
BRANCH_SWITCH=$3

if [ $BRANCH_SWITCH == "1" -a $PREVIOUS_HEAD != $NEW_HEAD ]; then
	# Start from the repository root.
	cd ./$(git rev-parse --show-cdup)

	# Check if any migrations have changed.
	CHANGED=`git diff $PREVIOUS_HEAD $NEW_HEAD --name-status | grep "^M.*migrations"`
	if [ $? -eq "0" ]; then
		echo "Beware. These migrations have changed:"
		echo "$CHANGED"
	fi

	# Check if any migrations have been deleted.
	DELETED=`git diff $PREVIOUS_HEAD $NEW_HEAD --name-status | grep "^D.*migrations"`
	if [ $? -eq "0" ]; then
		echo "These migrations in the old branch were deleted, you should consider if you need to undo them."
		echo "$DELETED"
	fi

	if [ -n "$CHANGED" -o -n "$DELETED" ]; then
		echo "Run these commands to roll back these migrations:"
		echo "	git checkout $PREVIOUS_HEAD"
		echo "$CHANGED\n$DELETED" | sort -r | sed -e "s/_/ /g" -e "s/\// /g" | awk '/[a-z]+ migrations [0-9]+/ { printf "\tpython manage.py migrate %s %04d\n", $3, $5-1; }'
	fi

	# Check if any migrations have been added.
	ADDED=`git diff $PREVIOUS_HEAD $NEW_HEAD --name-status | grep "^A.*migrations"`
	if [ $? -eq "0" ]; then
		echo "You also have some new migrations. Run them by using:"
		echo "	python manage.py migrate"
	fi

	# Check if submodules have been changed
	MODULES=`git diff $PREVIOUS_HEAD $NEW_HEAD --name-status | grep "\.gitmodules$"`
	if [ $? -eq "0" ]; then
		echo "The submodules in this project has changed. Update submodules by running:"
		echo "  git submodule update --init"
	fi
fi